USN-1284-1 fixed vulnerabilities in Update Manager. One of the fixes
introduced a regression for Kubuntu users attempting to upgrade to a newer
Ubuntu release. This update fixes the problem.

We apologize for the inconvenience.

Original advisory details:

David Black discovered that Update Manager incorrectly extracted the
downloaded upgrade tarball before verifying its GPG signature. If a remote
attacker were able to perform a man-in-the-middle attack, this flaw could
potentially be used to replace arbitrary files. (CVE-2011-3152)

David Black discovered that Update Manager created a temporary directory
in an insecure fashion. A local attacker could possibly use this flaw to
read the XAUTHORITY file of the user performing the upgrade.
(CVE-2011-3154)

This update also adds a hotfix to Update Notifier to handle cases where the
upgrade is being performed from CD media.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 11.10:
update-manager-core 1:0.152.25.8

Ubuntu 11.04:
update-manager-core 1:0.150.5.2

Ubuntu 10.10:
update-manager-core 1:0.142.23.2

Ubuntu 10.04 LTS:
update-manager-core 1:0.134.11.2

Ubuntu 8.04 LTS:
update-manager-core 1:0.87.33

In general, a standard system update will make all the necessary changes.